impl serde for metrics

Author: Frando

portmapper/src/metrics.rs

@@ -1,7 +1,8 @@
 use iroh_metrics::{Counter, MetricsGroup};
+use serde::{Serialize, Deserialize};
 
 /// Enum of metrics for the module
-#[derive(Debug, Default, MetricsGroup)]
+#[derive(Debug, Default, MetricsGroup, Serialize, Deserialize)]
 #[metrics(name = "portmap")]
 pub struct Metrics {
     /*